Adjustable propeller



Feb. H, 1947. RIDE FILIPPIIS 2,415,423

ADJUSTABLE PROPELLER Filed May 13, 1944 2 Sheets-Sheet 1 Fe; H, 1947.

R. DE FILIPPIS ADJUSTABLE PROPELLER Filed May 13, 1944 2 Sheets-Sheet 2 f v VENTUR- Patented Feb. 11, 1947 UNITED STATES PATENT crews 3 Claims.

This invention relates to adjustable propellers, and to means for setting the same.

One object of the invention is to provide a device of the character described having improved means responsive to centrifugal force for chan ing the setting of the propeller blades. within certain limits, the speed of a propeller may vary with the load thereon or the reaction thereto, the improved means referred to may be said to be responsive to the load on the propeller.

Another object of the invention is to furnish a device of the nature set forth wherein the pitch of the propeller or the angle of incidence of its blades varies with a centrifugal force that varies with the propeller speed; and wherein the diameter of the propeller or effective length of its blades vary with a centrifugal force that depends on propeller speed; these objects may be individuall or jointly realized.

Another object of the invention is the provision of a device of the class alluded to having improved means responsive to centrifugal force of a propeller blade or of an associated element for setting the propeller; and a related object is to so construct and arrange the element that it constitutes a mounting or bearing portion for the blade.

Another object of the invention is to construct a device of the type mentioned having improved highly compact means for yieldingly resisting the adjusting movement and for retracting the blades to an initial position, which may be settable.

Another object of the invention is to provide a device of the character described having improved means for positively controlling the propeller against the centrifugal force and for furnishing additional bearing structure for the propeller blades; a related object is to furnish a common manual control for a plurality of blades serving as a unit to afford a common bearing for alined blades.

Another object of the invention is the provision of a device of the nature set forth wherein a centrifugal control system for propeller blades, comprising a resisting spring, is cushioned against vibration by a cooperating hydraulic means or the like.

Other objects and advantages of the invention will become apparent as the specification proceeds.

With the aforesaid objects in view, the invention comprises the novel features, combinations and arrangements of parts hereinafter described in their preferred embodiments, pointed out in the subjoined claims, and illustrated in the annexed drawings, wherein like parts are designated by the same reference characters throughout the several views.

In the drawings:

Figure 1 is a view in front elevation with parts removed and other parts in section showing a device embodying the invention.

Fig. 2 is a centralhorizontal sectional view thereof with parts in elevation and parts removed.

Fig. 3 is a fragmentary view in front elevation with parts in section showing a modification of the invention.

Fig. 4 is a fragmentary central horizontal sectional view thereof with parts in elevation.

The advantages of the invention as here outlined are best realized when all of its features and instrumentalities are combined, but, useful embodiments may be produced involving less than the whole. a

It will be obvious to those skilled in the art to which the invention appertains, that the same may be incorporated in several different constructions. The accompanying drawing, therefore, is submitted merely as showing a preferred exemplification of the invention.

Referring in detail to the drawings, l0 denotes a device embodying the invention and showing, schematically, a hollow motor drive shaft l I having an end or front disc-like flange 12 connected thereto. Bolted to the member 52 at 13 is an annular ring it which may be made in one piece or split along a central line 15. Integrally formed on each ring section is a flange It in whichis journaled a stub shaft I! that may be an integral part of a propeller blade 18. Interengaging the bearing element Iii and the stub shaft I1 is a helical thread such that radial motion of the blad is accompanied by angular motion thereof about its longitudinal axis. Preferably the helical thread may consist of a series of angular grooves is equally angularly spaced apart, the bearing element it having projections or pins 20 whose inner ends extend into the grooves. The grooved arrangement described permits the provision of a conventional thread 2| for engagement with a nut or disc 22, whereby a powerful expansion coil spring 23 is engaged around the stub shaft 1?, between the bearing element 16 and the member 22. Thus the spring 23 yieldingly resists outward longitudinal movement of the propeller blade 93, and this may be adjusted by setting the member 22 to vary the initial tension on the spring. Thus the effect of centrifugal force on the blade I8 is to cause a combined radial and angular movement of the blade about its longitudinal axis, this being resisted by the spring 23, and occurring only when the centrifugal force attains a predetermined amount. The radial and angular movements referred to may bear a desired ratio to each other which ma progressively vary. At high elevations, as the density of the air diminishes, a variable speed motor may substantially increase the speed of the propeller and thus cause an automatic corresponding increase in the diameter of the propeller, and change the pitch of the blades thereof for an increased grip on the atmosphere. From another point of view, as an airplane ascends, and the density of the atmosphere diminishes, the reaction on the propeller diminishes so that the motor speed may increase and hence the propeller may undergo the described centrifugally caused changes in diameter and in pitch, to thus increase the overall efiiciency of the aircraft.

If desired, a remote control of any suitable character may be employed to control the described setting movements of the propeller in aid of or in opposition to centrifugal force, to enhance or regulate the operations mentioned, or to independently control the same as in the event that the springis inoperative. The type of control shown has been chosen forits simplicity and compactness and because it affords supplemental bearings for the stub shaft of each propeller blade. The structure described includes a cylinder that may be affixed to the flange l 2 as by brackets 26 and bolts or screws 2! so as to be in permanent true alinement with the propeller blades. Within this cylinder are pistons 28 for the piston rods 29 which extend through the heads 30 that may be threadedly or otherwise connected to the cylinder 25. These piston rods may constitute integral extensions of the stub shafts l'l. Connected to the cylinder is a center tube 3! and end tubes 32, 33, so arranged that if pressure is supplied through tube 3!, the pistons 28 are caused to move apart, liquid bleeding from the end tubes 32, 33. If pressure is supplied to the latter, the pistons 28 are caused to move toward each other with pressure bleeding from the center tube 3|. Any suitable valve control for the liquid may be provided, in a proper circulatory system, calibrated so that the piston of a manual indicator or control piston will directly indicate the amount of liquid supplied for projection or retraction of the propeller blades and consequently the true position of the latter. These tubes 3 l, 32, 33 may conveniently extend through the hollow shaft H to the manual control or pump within easy access of the pilot.

It will now be apparent that the hydraulic control may act in aid of or in opposition to the centrifugal force or the yielding element 23, and may wholly independently control the setting of the v propeller in the event that the yielding element is broken. Further, it will be seen that the cylinder 25 and the pistons 28 afford supplemental alining bearings for the propeller blade shafts and that the heads 3!] and piston rods 29 provide additional supplemental bearings. Since the cylinderZS is common to both propeller blades, there is in eifect a unitary alining bearing for both blades. Thus the strain on the bearings I6 is greatly relieved. Angular movement is in no way impeded because the piston and its connecting rodcan freely turn with its individual stub shaft l 7. Another important advantage is that the hydraulic control unit may serve as a vibratiton cushionforthe propeller blade. This may be accomplished by utilizing a fine bleeder connection between opposite sides of each piston, or by relying on a suitable predetermined minute clearance between the pistons 28 and the cylinder, when the conduits 3|, 32, 33 are closed. Such clearance, too small to show in the drawings, will serve as a reliable bleeder, particularly as a change in setting of the propeller due to centrifugal force is relatively slow. Yet any vibration which cannot be damped out by the yielding element 23, may be taken care of by the hydraulic unit which may be eflicient for a different frequency of vibration. A simple system of assembling is provided for, in which all parts connected to a blade are assembled therewith on a sector l4, after which the piston is inserted into the cylinder, the head 30 secured, and the sector fixed by the bolts l3.

In Figs. 3 and 4 is shown a modificatiton 35 illustrating the use of centrifugal force on an element other than the propeller blade, the latter being fixed against radial movement but being angularly settable about its longitudinal axis. Here a source of power such as a hollow drive shaftiifi may have a disc-like head 37 provided with protruding bosses 38. Alternatively, the disc 37 may be regarded as bolted at 31a to a driver, the member 36 acting as a trunnion for a bearing. To each boss there may be suitably afiixed a thrust bearing 39 for the stub shaft 40 of propeller blade 4!. Secured to the boss for axial movement toward and away from the bearing 39 is a member 42. Each member 42 is in the form of a box open at one end at 43 and at a side '34 to thus slidingly engage the disc 31 and receive the boss 38 to provide a housing. The member t2 may thus have walls 45, 46 at an angle to each other, the wall 46 being desirably curved. Each stub shaft 48 may be like that at IT but has helical engagement only with the wall 45 of the member 42, as by any suitable thread or by the use of pins 4'! engaging in the angular grooves 48. Angular movement of the member 42 is prevented by studs dfia connecting the wall 45 to the boss 38, these studs being slidable in the boss, and clearing the propeller blade. An expansion coil spring 49 engages around the'stub shaft and resists outward radial centrifugal movement of the member 42 which has suilicient mass to enable it to set the pitch of the propeller blade. For this expansion spring, the member 42 forms a housing. Integrally extending from the wall it is a hollow portion 58 connected to a piston 5i slidable in a cylinder 52, the latter being closed by heads 53 provided with packing boxes 55 for the portion 50. The latter is arranged so that it can accommodate the stub shaft Ml upon outward movement of the member 42. Liquid pressure conduits 3i, 32, 33 hereinbefore described are connected to the cylinder through the hollow shaft 33. If desired a small opening 55 may be provided through the hollow portion 59 at an inner end thereof to afford substantially equal pressure areas at-opposite sides of each piston, but this opening may be omitted.

In use, centrifugal action causes the member 42 to move outwardly against the force of the spring 49, thus causing angular movement ofthe stub shaft, 40 and hence of the propeller blade, the stub shaft entering the hollow portion 50. During this time hydraulic pressure effects may be zero or balanced, or may be increased in aid of or in opposition to the centrifugal force. If the spring 49 should fail, the hydraulic means may be used as the sole control. For retraction, pressure may enter the cylinder at the outer side of the piston and may flow through opening 55 into the hollow portion, if required, this portion being otherwise closed by the stub shaft 40. The operation and advantages will be the same as described in detail for the device ID, the main difference being that the propeller blades are not radially movable, and a different body is used for a source of centrifugal power.

It may be added that the direction of rotation of the blades and the angle or incidence of the helical threads l9 and 48 may have such relation to each other as to aid or oppose the centrifugal force tending to change the pitch of the propeller. In the device [0 such relation would naturally also affect the radial movement of the propeller blades.

This invention is applicable not only to aircraft propellers but also to ship propellers, air blowers, fans, etc., operated by variable speed motors. The radial movement and change in pitch may be made as great or as small as necessary within the limits of good engineering practice. The common manual control may be mechanical or hydraulic; if the former, a cam, gearing, toggle or the like, may be used actuated by a piston, rack and pinion or the like; and the propeller may have asmany blades as desired. The initial positions of the blades may be adjusted manually or hydraulically. In each case the setting structure should be balanced so as to be capable of acting as a flywheel for the propeller. The hydraulic means may serve as a dash pot or vibration damper to supplement the resilient means.

I claim:

1. A device including a hub having means including bearings, propeller blades having end portions rotatably and slidably mounted in said bearings for radial outward movement in response to centrifugal force on the blades, said bearings and said end portions having means including helical threads whereby a change in pitch of the blades is caused upon radial movement thereof, springs engaging said end portions for automatically causing retraction of the blades, and hydraulic means engaging said end portions for radially moving. said blades inwardly and out wardly. at will, in aid of or in opposition to said springs.

2. A device including a propeller having blades, a hub having bearings alined with the blades and in which the inner end portions of the blades are slidable upon outward radial movement of the blades in response to centrifugal force, the bearlugs and the end portions having splined means disposed to cooperate along arcuate paths to cause change of pitch of the blades upon radial inward and outward movement thereof, the end portions of the blades projecting inward beyond the bearings, expansion coil springs around the projecting parts of said end portions, the latter having enlargements and the springs acting between the enlargements and the bearings to automatically retract the blades, and hydraulic means including a cylinder and pistons therein connected to the said end portions adjacent to the said enlargements, whereby the blades are moved inwardly or outwardly, at will, in aid of or in opposition to said springs.

23. A device including a propeller having alined blades, a hub having spaced alined bearings, the blades having trunnions slidable in the bearings for radial outward movement of the blades in response to centrifugal force on the blades, the trunnions being angularly movable inthe bearings, the latter and the trunnions having means including a helical thread whereby the pitch of the blades is changed by radial inward and outwardmovement thereof, the trunnions projecting toward each other beyond the bearings, expansion coil springs around the projecting parts of the trunnions, the springs bearing at their outer ends on the bearings and at their inner ends being connected to the trunnions for automatically retracting the blades, the trunnions terminating in spaced relation to each other, a cylinder between the trunnions alined therewith, pistons in the cylinder, rods connecting the pistons with respective adjacent trunnions to cause inward and outward radial movement of the blades in aid of or in opposition to said springs, and means for admitting a power fluid to the cylinder to thus actuate the pistons, said rods being rigidly connected to the trunnions and the pistons to thus afford additional bearing for mounting the blades.

RAYMOND DE FILIPPIS.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 

